Add Close Application Button in Select Tool Menu for Touch-Only Devic…

…es (#12091)

* Add Close Application Button in Select Tool Menu for Touch-Only Devices

This commit introduces a "Close Application" button to the Select Tool menu in QGroundControl. The addition addresses the need for an accessible close option on touch-only devices that lack a physical keyboard (e.g., Steam Deck). By integrating this button directly into the interface, users can easily exit the application without requiring keyboard input, improving usability on mobile and handheld platforms.

* Update MainRootWindow.qml

QGroundControl.appName variable instead of "QGroundControl"

src/UI/MainRootWindow.qml

@@ -334,6 +334,18 @@ ApplicationWindow {
                             }
                         }
 
+                        SubMenuButton {
+                            id:                 closeButton
+                            height:             toolSelectDialog._toolButtonHeight
+                            Layout.fillWidth:   true
+                            text:               qsTr("Close %1").arg(QGroundControl.appName)
+                            onClicked: {
+                                if (mainWindow.allowViewSwitch()) {
+                                    mainWindow.finishCloseProcess()
+                                }
+                            }
+                        }
+
                         ColumnLayout {
                             width:                  innerLayout.width
                             spacing:                0